A drone strike conducted by the US military in Somalia has killed over 150 fighters from the Islamist group Al-Shabaab, a Pentagon spokesman said. The strike targeting the group's training camp was carried out over the weekend.

Officials said Monday that the drone strike was carried out over the weekend and dropped Hellfire missiles on a camp located about 120 miles (195 km) north of the Somali capital of Mogadishu.

"The fighters were there training and were training for a large-scale attack. We know they were going to be departing the camp and they posed an imminent threat to US and [African Union] forces," Pentagon spokesman Captain Jeff Davis said.

"Initial assessments are that more than 150 terrorist fighters were eliminated," he added.

No civilian casualties are believed to have resulted from the strike, Davis said.

A large number of militants were gathered in the location, “in formation" to conduct "some kind of ceremony" when the airstrike occurred, an official said.

Al-Shabaab, an Al-Qaeda affiliate, has been linked to a number of terrorist attacks in Somalia, and controlled large parts of the capital of Mogadishu from until they were forced out by African Union forces in 2011. The terror group remains devoted to toppling Somalia’s Western-backed regime.

This weekend’s strike is only the latest in a series of drone operations against the militant group, launched from a US airbase in the neighboring Djibouti. In September 2014, an airstrike killed the group’s leader, Ahmed Abdi Godane.